Sir Alex Ferguson is plotting a January transfer raid for at least two of Manchester City’s top targets in a move sure to infuriate Roberto Mancini ahead of Sunday’s derby.

Sportsmail can reveal that Manchester United chief executive David Gill flew to Croatia on Tuesday for talks about signing Dinamo Zagreb’s £15million-rated teenage sensation Alen Halilovic.

United's front: Manchester United have discussed the possible transfer of Sime Vrsaljko and Alen Halilovic

Mindful of Ferguson’s need for more defensive cover, Gill also enquired about 20-year-old right back Sime Vrsaljko and could now follow up with an audacious £20m double deal for two of Croatia’s hottest prospects.

Gill returned to Manchester on Wednesday and took his seat in the directors’ box for the Champions League tie with Cluj, confident that United are now in pole position to complete a transfer coup at City’s expense.

A third City target, Dinamo Dinamo midfielder Mateo Kovacic, also cropped up in Gill’s discussions. United asked about him in the summer but were put off by a £10m asking price.

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Halilovic, 16, is expected to develop into an even more accomplished attacking midfielder than Luka Modric and is on the radar of Real Madrid as well as both Manchester clubs.

United made their move after being alerted to an approach by City that was given short shrift by Dinamo’s sporting director Zdravko Mamic, who said: 'I have seen the reports about City offering £7m for Alen, but that would not even buy his left leg.'

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Gill’s transfer mission will do little for City manager Mancini’s mood in the build-up to Sunday’s eagerly awaited derby at the Etihad Stadium.

Mancini was left fuming at the way City missed out on the likes of Arsenal striker Robin van Persie in the summer and will demand answers if they are once more outmanoeuvred by their nearest, less noisy neighbours, who are also tracking Dinamo centre back Domagoj Vida.